LCS corrosion no serious problem, U.S. Navy and analysts say

MOBILE, Alabama -- Corrosion problems on the USS Independence, the first littoral combat ship built in Austal USA's Mobile River shipyard, don't endanger the program, according to analysts and Navy officials.

"I don't think it's a serious problem," said Loren Thompson, a defense analyst with the Arlington, Va.-based Lexington Institute. "It's typical of what happens when radical concepts are introduced for the first time. Some simple fixes should allow the Austal version to go forward."

Chris Johnson, a spokesman for the Naval Sea Systems Command, said the "aggressive" corrosion in Independence's propulsion system, confirmed in a letter to Congressional appropriations committees last month, is in no way catastrophic.

"You have to realize, from the Navy's perspective, the first ship of any class is a prototype," Johnson said. "You build it, you start testing it, you find what works and what doesn't work. ... We found a design issue, and we're working to correct it."

'It's a perception issue'

View full sizeAustal USA workers prepare to attach the bow of a littoral combat ship under construction Friday, May 27, 2011 in Mobile, Alabama. (Press-Register/Mike Kittrell)

That kind of approach is par for the course with the Navy, defense analysts said. The only difference with the Independence, said Jay Korman, of the Washington D.C.-based Avascent Group, is that it is an aluminum-hulled vessel, the first time the Navy has used that material in a major warship.

"It gives fodder to people who for so long have said that buying an aluminum ship would be problematic for the Navy," Korman said. "It's a perception issue as much as structural issue."

Austal is Mobile's largest industrial employer, with about 2,100 workers at its shipyard on the east bank of Mobile River. It's also one of the fastest-growing companies in the area, with plans to add about 130 workers a month over the next year or two, topping out at about 4,000.

Two military contracts are fueling that growth. In 2008, the Navy hired Austal to build lightly armed transport ships. The potential 10-vessel deal would be worth about $1.6 billion. And in December, the Navy said it intended to spend $3.6 billion for 10 littoral combat ships with Austal as the prime contractor.

Austal's design is one of two being built for the LCS program. A Lockheed Martin-led team is building a steel-hulled LCS in Wisconsin. The first version of that ship, the USS Freedom, also suffered a setback during sea trials, as the Navy found a long crack in its hull earlier this year.

Austal built the Independence and is working on a second LCS, Spearhead Coronado, as a subcontractor for General Dynamics-owned Bath Iron Works.

Independence has been in sea trials for more than a year. On June 17, the Navy announced the ship was experiencing galvanic corrosion in the water jets that power it.

How galvanic corrosion happens

Galvanic corrosion occurs when different metals are in close proximity within an electrolyte, like salt water.

Aluminum is more prone to corrosion and oxidation than the stainless steel in the LCS propulsion system. In the saltwater environment, charged ions from the aluminum are attracted by the stainless steel, and that causes the aluminum to corrode much faster than normal.

Designers had tried to fight the problem 2 ways -- by coating the stainless steel water jets and by attaching a sacrificial anode system, which uses metals even more susceptible to corrosion than aluminum to take the biggest corrosive hit, Johnson said.

The Navy, along with Austal and General Dynamics, in 2010 began to be concerned that those methods weren't sufficient to keep the aluminum from corroding, Johnson said. Recent dive inspections confirmed those fears, he said.

The Navy is doing some short-term repair work to keep the ship running and plans to dry dock the ship next year to make a long-term repair.

Austal USA President Joe Rella said his company will use new anti-corrosion coating material on the LCS under construction now.

In addition, he said, Austal has been working with the Navy to design the long-term solution -- an impressed current cathodic protection system that will both monitor the electrochemical reactions taking place in the propulsion area and supply an electrical current to suppress the corrosion process.

Austal uses such a system on its large Westpac Express ferry, which the U.S. Marine Corps uses as a transport ship. The system will be added to Independence next year and to Coronado before it is launched, Johnson said.

"Not only do the active systems help eliminate the stray currents that cause galvanic corrosion," Rella said, "they can also alert the operators and maintainers if the ship is at risk of accelerated corrosion."

Johnson said that system will be more costly than the original anti-corrosion measures, but he did not know how much more costly. The system was included in Austal's baseline design for its 10-ship contract, Johnson said, so it will not change the cost of those vessels.

"Corrosion is always a factor," Rella said, "but with Jackson (LCS 6), we will deliver to the Navy an array of tested corrosion-management tools and processes that will allow our Navy partners to get these innovative, versatile platforms out into the field and completing vital national security missions."

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MIKE KITTRELL/Staff Photographer

A littoral combat ship, left, and a joint high speed vessel are under construction May 24 at Austal USA in Mobile.